1. Field of the Invention
This invention generally relates to component carriers and more specifically to a system for facilitating the handling of flatpack integrated circuit components during the production of electrical devices.
2. Description of Related Art
Semiconductor devices have matured from simple circuit elements into complex components provided in a variety of integrated circuit packages. This maturation has been accompanied by an increase in the complexity of handling these components during assembly and testing operations. It has become necessary to protect these devices from various sources of mechanical and electrical damage during manufacture and to provide a means for testing individual circuit components during assembly operations.
These needs have led to the development of chip carriers that are special enclosures or packages for housing and protecting an integrated circuit or the like during processing, production, testing and assembly operations. Generally chip carriers orient an integrated circuit during the production process, assure proper placement and alignment of terminals for testing and for insertion into a printed circuit board. Chip carriers eliminate stress from the terminals and seals found in such integrated circuits. Moreover they must now protect a component from mechanical and electrical damage and provide access to all terminals to facilitate component testing.
As the number of circuit designs and packages have proliferated, so have the number of chip carrier configurations. Indeed there are now different chip carrier structures for different integrated circuit packages, including chip carriers exclusively for flatpack integrated circuit components. Flatpack integrated circuit components are characterized by comprising a planar rectangular housing and at least two or four sets of spread, coplanar terminal pins extending from the edges of the housing essentially in the plane of the housing. For example the following patents disclose chip carriers for flatpack electronic circuits that include two or more retention arms:
U.S. Pat. No. 4,379,505 (1983) Alemanni PA1 U.S. Pat. No. 4,591,053 (1986) Alemanni PA1 U.S. Pat. No. 3,604,557 (1971) Cedrone PA1 U.S. Pat. No. 3,652,974 (1971) Tems PA1 U.S. Pat. No. 4,409,733 (1983) Alemanni PA1 U.S. Pat. No. 4,535,887 (1985) Egawa PA1 U.S. Pat. No. 4,556,145 (1985) Putnam PA1 U.S. Pat. No. 4,991,714 (1991) Clatanoff PA1 U.S. Pat. No. 5,026,303 (1991) Matsuoka et al PA1 U.S. Pat. No. 4,549,651 (1985) Alemanni PA1 U.S. Pat. No. 4,620,632 (1986) Alemanni PA1 U.S. Pat. No. 4,747,483 (1988) Grabbe PA1 U.S. Pat. No. 4,767,984 (1988) Bakker PA1 U.S. Pat. No. 4,747,483 to Grabbe discloses a carrier for receiving a flatpack integrated circuit component. A stamped metal securing member comprising three spaced, essentially parallel legs secures the integrated circuit component in the carrier. The securing members are separate components that are loaded into the carrier and over the corners of the legs. The middle legs of these securing members and bases of the outer legs are welded to the frame. As a result a force applied a base of each clip produces a stress that pivots the tips of the outer legs about weld points to open the carrier.
U.S. Pat. No. 4,379,505 to Alemanni discloses a one-piece integrated circuit carrier including a base with a central opening bounded on opposite ends by walls having a plurality of narrow grooves for receiving the leads of an integrated circuit flatpack component. Resilient retaining fingers at the corners of the central opening extend diagonally into the opening. Each finger has a tip with a flange for fitting over the outermost leads of the flatpack component. The bottoms of the resilient fingers are displaced upward by vertical forces to spread them apart sufficiently and allow a flatpack electronic circuit component to be inserted in the opening. When the force is released, the retaining fingers return to their normal position and extend over the tops of the outermost leads to capture the flatpack package.
U.S. Pat. No. 4,591,053 issued to Alemanni discloses a one-piece circuit carrier including a base with a central opening bounded at opposite ends by walls having narrow parallel elongated grooves for receiving the leads of an integrated circuit. A pair of elongated resilient retaining fingers extend along opposite edges of the opening for connecting to the four outermost leads of the flatpack component to hold it in the carrier. A flatpack component is inserted by pushing generally horizontally outward on the tips of the retaining fingers to spread them apart and allow the flatpack to be inserted. When this horizontal force is removed, restoring forces in the fingers return them to their normal positions extending over and frictionally contacting the outermost leads of the flatpack component.
It has also been proposed to utilize biased pivoted arms to engage other portions of flatpack electronic components as, for example in the following patents:
U.S. Pat. No. 3,604,557 to Cedrone discloses a carrier for small objects including flatpack electronic components formed as a distortable parallelogram. When the structure is oriented in a capture position, rabbets overlie a component housing.
U.S. Pat. No. 3,652,974 to Tems discloses a module carrier that includes overlying retaining elements that capture the housing of the electronic circuit component.
U.S. Pat. No. 4,409,733 to Alemanni discloses a carrier for a flatpack component. Upstanding arms deflect pivotally about a horizontal axis to an open position to allow the flatpack to be inserted. When the arms are released, they pivot to the vertical position and lugs at the ends of the arms overlie and engage the housing.
U.S. Pat. No. 4,535,887 to Egawa discloses a carrier for flatpack integrated circuits that includes a receiving section with lead-accommodating grooves for supporting the various leads from the integrated circuit. A pair of pivotally supported latch members with arms that retain the integrated circuit package in the carrier by providing a stable support at each corner of the integrated circuit package. A detent-like mechanism retains the arms in a locked position.
U.S. Pat. No. 4,556,145 to Putnam discloses a one-piece flatpack chip carrier including a pair cantilevered arms having tapered heads for holding chips of varying thicknesses. The arms extend into a carrier central aperture from the top and bottom side of the aperture respectfully Longitudinally offset stops mounted on the arms stabilize a small chip laterally and longitudinally. Chips of varying widths may be held between the heads of the arms up to the width of the central aperture.
U.S. Pat. No. 4,991,714 to Clatanoff discloses a carrier device with a central opening and a pair of beams extending into the opening. Each beam has hooks to grasp a component. A series of interconnected bars join to the beams to allow flexing whereby the carrier is enabled to accept a component between the hooks and to bias the beams toward each other to contain the component.
U.S. Pat. No. 5,026,303 to Matsuoka et al discloses a flatpack integrated circuit carrier. Diagonally disposed, movable flexible arms with engaging claws at an upper free end of each arm engage at upper edge of the corner portion of the integrated circuit housing. .The arms retract or move outwardly along the diagonal lines to enable the insertion and removal of the integrated circuit component.
Somewhat similar structures embodying flexible arms or capture structures for engaging an integrated circuit housing have been proposed for pin grid array integrated circuits. These structures are disclosed in:
The use of flexible or pivoted arms or retaining fingers that rely on the inherent resilience of a molding material can limit the useful life of the carrier. When the material is stressed by bending a finger, the finger does not return to its original position on release. The amount by which a finger fails to return to its original position increases with use. Eventually the finger will not return to a positive locking position whereupon the carrier is no longer useful.
Each of the foregoing patents provides a structure that requires special tooling for use. For example, each requires tools for applying a horizontal or vertical fores to move the retention means to an "open" position to allow the insertion or removal of the component. Such tooling must extend past the same position at which the insertion or removal occurs. Otherwise the bias of the restoring forces in the retention mechanism would close the opening and prevent removal or insertion
Other mechanisms for engaging integrated circuit components include those discussed in:
U.S. Pat. No. 4,767,984 to Bakker discloses a carrier for a flatpack integrated circuit component that supports the leads. A diagonal slot at each corner of the carrier receives an arm that pivots about an horizontal axis at right angles to a the slot between open and closed positions without introducing any return bias. Thus this structure enables assembly apparatus to open the arms at one location that is remote from a component insertion or removal position. However, the force moving the arm is applied vertically or at right angles to the plane of carrier. Consequently carrier motion must be interrupted to allow the arm to pivot.
Structures involving discrete components such as shown in the Baker and Grabbe patents tend to overcome the limited life of carriers with resilient arms. However, the locking structures require an application of force at right angles to the direction of normal chip carrier motion. This force is not readily applied while the chip carrier is in motion, so the chip carrier must stop along the assembly line to enable the appropriate apparatus to open or close the retaining structure.